[PSUBS-MAILIST] coarse vs fine thread

[Alec Smyth via Personal_Submersibles]

Ah, I have pondered something related for ages. I have an aluminum bow dome
retaining ring bolted to an aluminum seat. I used aluminum screws, to
reduce galvanic pair issues. And then I broke off one of the screws by pure
clumsiness. I will have to drill this out, as there's virtually no stub,
and will probably end up with one screw larger than the rest if I need to
re-tap. But my question is... would you guys recommend using aluminum
screws in this scenario? I am not really concerned about their holding
power, there's a large quantity of screws involved.

Best,

Alec

On Sun, Mar 22, 2015 at 3:09 PM, Adam Lawrence via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>  Hi guys,
>
> There really isn't an appreciable difference in performance between coarse
> and fine threads. The more important questions are bolt/nut
> material, thread engagement and torque.
>
> The argument for sticking with coarse threads would be that you reduce the
> chance for cross threading the wrong bolt during assembly, since coarse
> threads are predominately used.
>
> Adam
>  ------------------------------
> *From:* Personal_Submersibles [mailto:
> personal_submersibles-bounces at psubs.org] *On Behalf Of *Sean T Stevenson
> via Personal_Submersibles
> *Sent:* Sunday, March 22, 2015 1:13 PM
> *To:* Personal Submersibles General Discussion
> *Subject:* Re: [PSUBS-MAILIST] coarse vs fine thread
>
>  Helicoils are an option.
>
> Sean
>
>
> On March 22, 2015 11:58:31 AM MDT, Rick Patton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>>
>>  Hank
>>
>> Fine is the only way to go as aluminum is a much softer metal than steel
>> so it will strip much easier so the more metal you grab, the better, which
>> fine threads will give you.
>>
>> Rick
>>
>> On Sun, Mar 22, 2015 at 5:55 AM, hank pronk via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Help I need advice!
>>> My new bow dome will be secured to the Al mating ring with straps.  I am
>>> laying out the bolt holes to be threaded in the AL ring.  My question is,
>>> should the bolts be fine or coarse thread? What holds better in AL ?  The
>>> threads will be 3/8 by 1 in deep.
>>> Thank you in advance.
>>> Hank
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>>>
>>
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